1. Field of the Invention
This invention relates generally to a retractable/extendable step. More particularly, the present retractable step interfaces with the CAN bus in modern vehicles to signal when to extend and retract a vehicle step to assist entry into the vehicle.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
High ground clearance vehicle such as trucks, SUV's and four wheel drive vehicle typically create a problem for people to get into because the distance between the ground and the floorboard of the vehicle can be great. To reduce the height of the step, fixed running boards are often installed. While the fixed running board makes entry into the vehicle easier the fixed running board defeats the purpose of the vehicle having high ground clearance. Another solution is to provide an extendable/retractable step. These steps are usually wired to the door switch of the vehicle to extend and retract the step based upon the status of the door switch. Wiring the step into the vehicle usually requires removal of door or interior panels to gain access to the switch wiring. Car dealers and new vehicle owners are often apprehensive to have modifications made to the interior of their new vehicles and possibly voiding the new car warranty. There is a need to provide a step signaling mechanism that minimizes disassembly of the interior of a vehicle. Some patents have been published and issued on systems that describe signaling systems to extend and retract a truck step. Exemplary examples of patents covering these products are disclosed herein.
U.S. Pat. Nos. 6,942,233, 7,398,985, 7,413,204 and 7,584,975 issued to Horst Leitner disclose Retractable Vehicle Steps. These retractable vehicle steps require the installer to cut into the electrical system of a vehicle to obtain power for the retractable step and also require the installer to connect into the door switch on all the doors where the step will be extended. This requires running a significant amount of wiring to each door, to a controller and to the extension mechanism. Some of these patents also disclose using the key fob that unlocks the door to extend a step. While these patents disclose an extendable and retractable step, they either rely upon wiring the system into a door switch or the key fob that can leave a step extended until some signal that retracts the step(s).
U.S. Pat. No. 7,081,816 issued Jul. 25, 2006 to Dean David Schebal et al., discloses a Compact Wireless Sensor. The sensor is for placement in a door or window and sends a signal when the door or window is opened. The signal does not activate a step to extend or retract and further does not send a complimentary signal to indicate when the door or window has been closed. The device uses a timer to sample the state of the sensor and send updated information only when the timer initiates a reading and the status changes. This sensor is configured for installation within a wood doorjamb and is not configured for installation into an automotive door.
U.S. Pat. No. 7,692,542 issued Apr. 6, 2010 to Allan Outzs discloses a Door Position Monitor that couples a magnetic field through the door to determine the status of the door. The sensor uses a wired connection to a magnetic reed switch to determine the status of the door. While this patent determines the status of the door it does not transmit a wireless signal to activate a step for entry or exit from a vehicle.
Modern vehicles have an integrated CAN bus (controller area network). The CAN bus is a vehicle bus standard that is designed to allow microcontrollers and devices to communicate with each other within a vehicle without a host computer. The protocol was released in 1986, came to market in 1987 and was mandatory on cars and light trucks sold in the US since 1996. This specification has two parts; part A is for the standard format with an 11-bit identifier, and part B is for the extended format with a 29-bit identifier. A CAN device that uses 11-bit identifiers is commonly called CAN 2.0A and a CAN device that uses 29-bit identifiers is commonly called CAN 2.0B.
What is needed is a wireless sensor that can be glued, bonded or otherwise secured to or near a door of a vehicle to determine when a door is opened or closed to signal a step to extend or retract the step based upon the status of the door. Accordingly, a wireless sensor and transmitter to operate a vehicle step which overcomes the above-stated problems is desired.